A lead made of a rectangular copper wire is bonded to the solar battery cell in order to extract an electrical output. The lead shrinks when it is cooled from a high-temperature state immediately after bonding to an ordinary temperature. The shrinkage of the lead causes warpage or local deformation of a substrate, thereby causing cracking in the solar battery cell.
Lead bonding electrodes that extend linearly are formed on a light receiving surface (a front face) of a semiconductor substrate constituting the solar battery cell in order to bond the lead. On the other hand, lead bonding electrodes are formed in a dot shape (in a form like stepping stones) on a rear surface of the substrate with a predetermined gap therebetween also to bond the lead. A portion other than the lead bonding electrodes formed in a dot shape on the rear surface of the substrate is made as an aluminum electrode across the substrate.
The lead bonding electrode can be continuously provided from one end to the other end of the semiconductor substrate along the lead. However, because the strength of a boundary portion between the aluminum electrode and the lead bonding electrode is low, when cracking occurs at any part of the lead bonding electrode, the cracking spreads over the full length of the semiconductor substrate along the boundary.
To avoid this situation, conventionally, lead bonding electrodes have been formed in a dot shape (in a form like stepping stones) with a predetermined gap therebetween as described above. With this configuration, even when cracking occurs at any part of the boundary portion, the cracking does not spread to adjacent lead bonding electrodes (see, for example, Patent Literature 1).